An acrylonitrile butadiene-styrene (ABS) resin, which is prepared by graft-copolymerizing styrene and an acrylonitrile monomer with a butadiene-based rubbery polymer widely used in the industry, has characteristics such as impact resistance, processability, superior appearance, excellent mechanical strength, and high heat deflection temperature. Accordingly, an ABS resin is used in various fields such as automobile components, electric and electronic products, and building materials.
However, since an ethylenically unsaturated polymer is present in a butadiene rubber constituting an ABS resin, the ABS resin is easily oxidized due to ultraviolet rays, light, heat, and the like in the presence of oxygen. Accordingly, the appearance and color of the resin are changed and the mechanical properties thereof are deteriorated. Therefore, such an ABS resin is not suitable for external application.
Accordingly, an acrylate-styrene-acrylonitrile (ASA)-based resin providing superior weather resistance and aging resistance with superior properties and including an acrylic rubber, in which an ethylenically unsaturated polymer is not present, has emerged as an alternative. An ASA-based resin is mainly used for external application due to superior weather resistance, chemical resistance, thermal stability, and the like. In addition, an ASA-based resin is used as an end product itself without any treatment such as surface-coating, painting, or plating. An ASA resin is widely used for external electrical and electronic parts, building materials, sporting goods, automobile components, and the like. In addition, the resin is mainly applied to satellite antennas, kayak paddles, chassis joiners and profiles, door panels, automobile radiator grills, side mirror housings, and the like.
In addition, since an ASA-based resin does not require a post-process such as plating or painting, the resin has advantages such as reduced manufacturing cost and eco-friendliness. However, an ASA-based resin has disadvantages such as insufficient impact strength and non-luxurious appearance due to unaesthetic high gloss. Accordingly, demand for an ASA-based resin exhibiting low gloss is increasing.
To address this problem, a method of embossing a surface of an ASA-based resin or coating the surface with a low-gloss material has been applied. However, such a method causes processing cost increase, and decrease of low-gloss effect due to abrasion during processing. In accomplishing low-gloss effect without use of such coating methods or application of a pad, particle diameter is an important factor. When large-diameter particles having an average particle diameter of 1 μm or more are present on a surface of the resin, the smoothness of the resin surface is adjusted to be larger than the visible light region and thus the incident light is scattered, whereby low-gloss effect is exhibited. If an average particle diameter of an acrylate-styrene-acrylonitrile resin may be adjusted to 1 μm or more, low-gloss effect may be exhibited without application of a large-diameter ABS resin. However, it is difficult to prepare an ASA resin having an average particle diameter of 1 μm or more through emulsion polymerization. To prepare an ASA resin having an average particle diameter of 1 μm or more, bulk polymerization is generally performed. However, although an ASA resin with an average particle diameter of 1 μm or more prepared by bulk polymerization exhibits low-gloss effect, mechanical properties thereof are decreased. Therefore, there is a need for development of an ASA-based resin exhibiting superior low-gloss characteristic while providing superior mechanical properties and weather resistance.